This invention relates generally to hydraulic valves, and more particularly concerns a sequencing valve for use with reversible or cyclic hydraulic systems.
Many modern hydraulic circuits include elements which must be operated in a sequential or cyclic manner. For example, hydraulic circuits used in refuse compactors must operate so as to extend a ram and compact the refuse material; then, when the ram reaches the end of its stroke (or any obstruction), the hydraulic circuit must automatically operate so as to reverse the direction of ram travel and return the ram to its original or start position. In other machines and circuits, hydraulically powered motors must be operated to provide motion in a given direction, and thereafter must be operated in a reverse direction and return related machine elements to original or start positions. Machine operation must then be halted.
To provide the desired sequential control, hydraulic sequence valves have been offered. A line of such valves, which has met with great commercial success, are the positive sequencing valves offered by Modular Controls, Inc., Box. 38, Villa Park, Ill., 60181. For example, one such valve is designated as model PSV-1061-8T.
It is the general object of the present invention to provide an improved positive sequencing valve which will positively re-cock itself when the cycle of operation has been completed.
It is another object to provide a positive sequencing valve which will cause a controlled hydraulic element, such as a ram, to be operated first in one direction, and then in an opposite direction and, after the cycle of operation has been completed, which will return or re-cock itself so as to assure operation of the controlled element in the first direction once again when the hydraulic circuit is sequentially re-energized. A related object is to provide a valve mechanism within the valve which assures that this re-cocking action occurs rapidly so that the controlled element can be operated on a relatively continual basis if necessary.
Yet another object is to provide a valve of the type described which is inexpensive in its finished cost. A related object is to provide such a valve which is reliable in use and rugged in design. Another related object is to provide such a valve which will provide a long service life with minimal attention and maintenance.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings. Throughout the drawings, like reference numerals refer to like parts.